The present invention relates to coupling apparatuses, particularly coupling apparatuses used for forming a rack, display case or furniture by connecting rectangular flat sheet assembly members.
A conventionally known rack or case for displaying merchandise is formed by combining many blocks with plural couplings, with many frames to be connected to the plural couplings. In this case, while such a display case can be easily assembled or carried, the connected portions of couplings are liable to become loose, causing frames to easily disengage, to further cause shelves on them to drop, or to fall the frames. For this reason, in conventional coupling apparatuses, set-screws for preventing the loosening are additionally tightened in the connected portions between the couplings and the frames fitted thereto. However, in such coupling apparatuses, while the above mentioned trouble can be prevented, the screw tightening work for the connection is very troublesome, and when a number of the couplings and frames are used, fatigue is involved and the assembling efficiency is very low.
Furthermore, there are also conventionally known blocks with square or cylindrical couplings, each coupling of which has a rib protruding around it, so that the coupling may be inserted into a square or cylindrical frame through the rib. However, in this case, the coupling is fitted into the frame with striking the block by a hammer, or the like, and for removing, the block is struck by a hammer in the other direction. Therefore, in addition to low working efficiency, not only the coupling apparatuses but also the frames may be broken.
A conventional rack for displaying merchandise is formed by combining tubular frames or square frames horizontally and vertically. Many kinds of coupling members are used to combine these tubular and square frames. However, while attention has been recently paid to a rack which uses rectangular flat sheets, there are no couplings for combining them, and conventional couplings cannot be used for them at all.